The estimation and identification of the self-position is an essential capability for humans and machines. It is always important for robots and computer visions to know where the current position is. Particularly, in a navigation system of a mobile robot, it is a basic demand to keep track of where the current position is.
A position detection device disclosed in Patent Literature 1 is known. The position detection device includes an intensity image acquisition means that acquires an intensity image at the front view of a mobile body, a distance image acquisition means that has the same field of view as the intensity image acquisition means and acquires a distance image at the same time as when the intensity image acquisition means acquires an intensity image, a feature point extraction means that extracts a feature point from each of at least two sequential frames of intensity images, and a reference feature point selection means that calculates a displacement of the position of the feature point extracted by the feature point extraction means between the two frames based on the distance image and selects a reference feature point for calculating the self-position from the displacement.